Maxillary skeletal anchorage expanders (hereafter in the background called “expander(s)”) are devices used for a treatment of patients with transverse maxillary deficiency. With children, palatal expanders have been used to expand the maxillary arch to create room for the growth of permanent teeth or to widen the upper jaw so that the bottom and upper teeth will fit together better. In some cases, the jaw is expanded as a treatment to a compromised airway. Some known palatal expanders comprise and expand the maxillary arch by tooth (molar) borne anchorage means (bands) bridged together by an adjustable screw mechanism (see U.S. Pat. No. 5,564,920 Klapper). As the screw is turned, a bilateral force is generated against the teeth and jaws to cause displacement of the teeth and the maxillary arch. Once installed, the adjustable screw is rotated using a tool. The screw conventionally comprises two opposing halves, each half having a threaded portion. The force from the expanding screw is transferred through arms of the device to the banded molars and ultimately results in expansion of the maxillary dental arch and/or growth from the median palatine suture. The expander is left in for a therapeutically effective period and the patient, or patient's caregiver, activates the expander by rotating the screw a predetermined amount over a predetermined period appropriate to the expander screw configuration, age of the patient, and condition for which treatment is applied (e.g., a ¼ turn producing 0.25 mm of movement once per week; a ¼-½ turn a day producing 0.25-0.50 mm of movement a day, etc.). Following a desired expansion, a holding phase is performed, leaving the expander in place for 3-6 months for stabilization, during which time the screw is locked in place to prevent the screw from backing up. During the holding phase the tooth/jaw interface stabilizes in a new position and the palatine suture grows back together across the space, after which time the expander is removed. The expander described above expands the space across the palatine suture via forces that are directly applied to only the teeth.
Another known expander device is demonstrated in U.S. Pat. No. 9,351,810 (Moon). The Moon expander uses four mini screws/temporary anchorage devices to mount a pair of bodies to the ceiling of the hard palate on either side of palatine suture. Each of the bodies in Moon also comprise a pair of extending arms and a pair of tooth anchorage bands devices similar to that used by Klapper as mentioned above. The Moon expander comprises a double ended screw located between the pair of bodies. When the double ended screw in Moon is rotated, forces are applied directly not only to the teeth, but also by the mini screws to the hard palate on either side of the palatine suture. Unlike the Klapper device, since force is also applied directly to the hard palate, a reduced amount of force can be applied to the teeth, and a greater amount of force on the bone, which reduced force means stresses on the tooth/jaw interface can be reduced. However, the Moon expander also has a number of disadvantages. By applying forces directly to the hard palate, the mini screws are put under stress and thus are subject to potential breakage, as is also the bone structure in the area where the screws are inserted. Further, although Moon applies less force to the teeth, it nevertheless transmits force to and causes movement of the teeth, which may not be desired. For example, when treating transverse maxillary deficiency in skeletally mature individuals, transmitting force to the teeth can result in undesired alveolar effects, such as alveolar “bending,” tooth root resorption, and potentially even a “scissors bite.” Furthermore, Moon's expander is only supported by two mini implants on each side of the median palatine suture, which often times in more skeletally mature individuals is insufficient and inefficient at generating the desired orthopedic effects, such that could occur with surgical osteotomy followed by expansion. In these skeletally mature cases, the limit of only two mini implants on each side of the median palatine suture (4 in total) not only is inefficient at generating a desired orthopedic expansion, but also results in increased stresses on each individual mini implant and the bone around those implants. This is evidenced by the fact Moon's expander often time requires full activation of the expansion screw in skeletally mature individuals, which is 8-12 mm of activation, just to achieve opening of the median palatine suture and achieve 1-2 mm of orthopedic expansion. As a consequence of this inefficient skeletal expansion and as a consequence of the design lacking the ability to interchangeably attach different size expansion screws to the anchor bodies, in many cases when treating mature individuals, at least two of Moon's devices are required to achieve satisfactory skeletal expansion. Requiring multiple uninstallations and installations of the device causes patients to be subjected to multiple surgical procedures, increased cost, and discomfort, and requires greater effort by the clinician. Also, during the holding phase described above, the Moon expander device, as well as other known devices, requires that that it remain in a patient's mouth during the entire course of treatment. However, the expansion screw and other structures of the Moon device can disrupt tongue function and its expansion screw has a number of sharp edges, which over a long period of time can cause discomfort and potential sources of contamination.
One thing that is needed, therefore, is an expander that does not directly affect movement of teeth during expansion of the palatine suture, that enables the attachment of interchangeable expansion screws of different sizes, that reduces forces and stress applied to screws as well as the local bone supporting the screws and yet is able to more effectively distribute force along the median palatine suture, and that as well does not cause discomfort during the holding phase. Stated in another way, what is needed is an expander that can generate more substantial and efficient orthopedic effects than the prior art, while at the same time eliminating alveolar and tooth effects, and, reducing discomfort and inconvenience for the patient and clinician. Maxillary deficiency can also occur in a forward (sagittal) direction. An orthodontic device known as the Keles Facemask includes both a palatal expander and an orthodontic face bow that impart lateral and protraction forces via molar bands that are fixed to a patient's dentition. Jaw movement imparted by the Keles device causes forwardly directed downward growth of the maxilla. The Keles device relies on tooth borne forces that are then transferred to the maxilla, which is less than ideal, since movement that might otherwise be imparted to the maxilla bone is instead imparted to teeth.
Another device invented by De Clerck utilizes a bone anchor comprised of a Bollard miniplate to transfer forward protraction forces to the maxilla. The De Clerck device can be used for maxillary protraction, but it to causes rotation of the maxilla, which causes movement and growth of the maxilla to be directed not just forward, but downward, and as well requires relatively invasive mucosal surgery for installation.
What is needed is an orthodontic device that is able to impart forward movement and growth of the maxillary skeletal complex and the 9 bones that articulate with the maxilla in a manner that improves upon the prior art.